1) Field of the Invention
The present invention relates to a method of removing asbestos from asbestos-containing materials by 99% through low temperature heat treatment.
2) Background of Related Art
Asbestos is one of industrial source minerals utilized in industrial fields, and called with a product name or an ore name. The asbestos is a general product name, and serpentine, olivine or a mineral name is used as the ore name.
The industrial use of asbestos has been recorded since the early 19th century, and it has been known that the asbestos has been regularly mined in Canada, Italy, and the Soviet Union in the end of 19th century. In the early 20th century, the beginning of the use of the asbestos in a brake lining, a clutch, and a gasket of a vehicle rapidly increases the demand for the asbestos. The Second World War diversifies the use of the asbestos, so that millions tons of asbestoses are used to develop North America and reconstruct Europe. Even in Korea, all thatched roofs in farming areas are replaced with slate roofs as a part of Saemaeul movement.
Meanwhile, asbestos minerals are produced in the form of a fibrous assembly, that is, in the form of a bundle. In addition, the asbestos minerals are easily separated from a peripheral dry rock, and split into smaller pieces along a cleavage surface. The fibers represent high tensile force, and have a long length to the extent that the ratio of the minor axis to the major axis is in the range of 20 to 1000. When viewed by using naked eyes of a user, the fibers have the characteristics the same as that of organic fiber such as cellulose, and have flexibility to the extent that thread can be made. Meanwhile, all asbestos minerals are not harmful, and only the asbestos minerals having the fibrous structure are harmful. If a user inhales asbestos dust through a respiratory organ, health problems may be caused. However, even if the user inhales asbestos dust, a disease is not caused unconditionally. It is known that asbestos dust having the length of 5 μm or more, the diameter of 2 μm or less, and the aspect ratio of 5:1 or more is mainly attached to the fine structure of the lung to cause a disease. Although lung cancer appears to a user having a job causing the inhalation of a great amount of asbestos dust or inhaling the asbestos dust for a long time, the disease appears after 20 to 40 years since the user inhales the asbestos dust. Diseases caused by the asbestos include pulmonary asbestosis, lung cancer, celothelioma, and pleural thickening.
Since the asbestos is harmful in an environmental aspect as described above, the asbestos must be safely treated when the asbestos is wasted. Recently, even though most asbestos are buried in a proper place, the burial of the asbestos without the pre-treatment is restricted. Accordingly, since a pre-treatment process is indispensible so that the whole processes are complicated, high cost is increased, and an environmental pollution material after the burial of the asbestos is exposed, a technology of scientifically and safely treating the asbestoses at low cost is required. Especially, Korea designates all acts such as handling and moving of all materials including 1% or more of asbestos as illegal acts in 2011.
Among schemes of treating the asbestos developed until now, there are chemical treatment schemes including a scheme of removing the fibrous structure of the asbestos by treating the surface of the asbestos, and a scheme of melting the asbestos by heating the asbestos at a high temperature. According to the schemes, a bigger problem may be caused by a used solution rather than the harmfulness of the asbestos. In addition, energy may be significantly required, and the treatment cost is greatly required due to the high-temperature heating process. In addition, although the asbestos are removed by about 50% to about 90% according to a conventional scheme, the asbestos are legally restricted in the handling or the movement of the asbestos if at least 1% of asbestos are contained, so that a scheme of removing the asbestos by at least 99% is required.
As a related art of the present invention, there is Korea Unexamined Patent Publication No. 10-2012-0110425 titled “method of asbestos detoxification and calcium compound reaction liquid used therefore” published on Oct. 10, 2012.